What are the possible failure cases of React Native's AsyncStorage?

Question

React Native provides the AsyncStorage library as a way to store persistent data in RN apps. In general, AsyncStorage is pretty straightforward to use, except for one aspect:

Both of the main AsyncStorage functions, AsyncStorage.getItem and AsyncStorage.setItem return Promises. This is simple enough to understand: The actual querying or saving done by the function runs in the background, and the getting or saving of items might fail, requiring us to catch the error.

However, it seems that nowhere in the React Native documentation is it specified what, exactly, are the failure cases of AsyncStorage or which errors one should expect when calling setItemor getItem. Of course, one can deduce what might be a few of the error cases: One might try to getItem using an inexistent key, or one might try to setItem in a full or nearly full store, and the OS might refuse to release more disk space for your app, but it is frustrating not to have a full list.

It would be nice to know how exactly AsyncStorage might fail, so that people who are developing React Native apps which use data persistence might know exactly which failure cases they need to handle.

Answer 1

The code is open source, you can see when the calls fail, for example here on android or here for ios.

The getItem call, fails, for example when requiring a nonexistent item. Other example may be Failed to create storage directory. which you can see in the ios module (for example when there's not enough space on device).

Edit:

According to the documentation of react-native-community/async-storage ,getItem won't fail when requiring a nonexistent item, it will just return null.